The present invention relates to an automatically operated lathe and method for controlling the same.
A turning machine tool capable of performing an automatic turning process (referred generically to as an automatically operated lathe in this specification) may automatically carry out various turning processes in sequence or, if necessary, simultaneously, by causing a feed motion of various tools carried on a tool rest relative to a bar-shaped or disk-shaped workpiece to be machined, which is securely held in a spindle. Recently, an automatically operated lathe of a type (so called an electronic-cam type) controlling a relative feed motion between a workpiece or spindle and a tool or tool rest by a machining command using a cam-reference data for successively directing tool positions as a function of cam rotation angles has been provided.
In the electronic-cam type automatically operated lathe, an electric operating command following a predetermined cam curve is used, in place of a mechanical operation of a cam used in a traditional cam-installed automatic lathe, to automatically control a relative feed motion between the spindle and the tool rest. Accordingly, the electronic-cam type automatically operated lathe is capable of advantageously performing a relatively simple machining sequence in a short time, due to respective motions of tools carried on plural tool rests, which follow individual cam curves in a way similar to the conventional cam-installed automatic lathe. In particular, according to such an electronic-cam system, it is not necessary to provide many types of mechanical cams corresponding to the configurations of machined products, and it is possible to significantly reduce time and labor required for an initial set-up, which permits various kinds of products to be manufactured in very high productivity in comparison with the conventional cam-installed automatic lathe.
Also, in the electronic-cam type automatically operated lathe, even when the machine structure thereof is provided with a plurality of control axes along which the spindle and the tool rest are relatively operated, it is possible to prepare cam diagrams for the respective control axes on a common reference (i.e., a cam rotation angle), which advantageously makes it easier to program a synchronizing command of the control axes. Moreover, the operation of the control axes is individually and freely controllable, so that, in the case where various machining processes are successibly performed by using plural tools, it is made easier to operate the tools so as to overlap in time, and thereby, it is possible to significantly reduce the time required for the entire machining process (i.e., one machining cycle) of the workpiece to be machined.
In the above-described electronic-cam type automatically operated lathe, the cam rotation angle as a reference for preparing the cam diagrams may be defined on the basis of a rotational frequency of the spindle. That is, a predetermined rotational frequency of the spindle is defined to correspond to a single rotation (360 degrees) of the cam, and tool positions are successively directed correspondingly to the rotational frequencies of the spindle, so as to control the operation of the respective control axes. According to this structure, it is possible to individually control the operation of the plural control axes on the basis of a common reference defined by the rotational frequency of the spindle that is a mechanically operative component of the automatically operated lathe.
However, in this structure, the operation of the control axes cannot be controlled during a period when the spindle does not rotate. Therefore, it is difficult, in the automatically operated lathe performing an electronic-cam control on the basis of the rotational frequency of the spindle, to carry out, for example, a secondary process (e.g., a cutting process by a rotary tool) during a period when the spindle does not rotate, which can be carried out by a conventional multifunctional numerically-controlled (NC) lathe. Also, when the compensation of the tool position to be directed, i.e., a tool offset, should be commanded due to, for example, a tool edge wearing or a tool changing, it is required to prepare the cam diagram in which the tool position is shifted in a desired offset value. In this case, the rotational frequency of the spindle corresponding to a cam single rotation is not changed, so that the cutting feed speed of the tool relative to a workpiece to be machined is varied, which may result in changing the roughness of a machined surface.
Contrary to this, in the conventional NC lathe, since a relative feed motion between a spindle and a tool rest is controlled to continuously move a tool toward a designated position on the basis of an elapsed time under the designation of a feed speed in the desired control axis, it is possible to command a tool offset without varying the cutting feed speed of the tool. However, a time required for one machining cycle is somewhat readily varied due to the way of arranging a machining program and the selection of the numerical value of input data, so that an operator""s skill is necessary to efficiently program, for example, a synchronization command between plural control axes or a superposition command between axes-systems in a multi-axes, multi-path NC lathe.
Furthermore, in the case where various machining process are successively performed by using plural tools in the conventional NC lathe, it is generally difficult, from a viewpoint of machine and control structure, to perform a machining process of one tool until another tool reaches a stand-by position after finishing the machining process thereof, and thereby, the time required for one machining cycle inevitably includes the idle time of tools. In this respect, the electronic-cam type automatically operated lathe is capable of easily eliminating the idle time of tools as already described and, therefore, of effectively reducing the time required for one machining cycle in comparison with the conventional NC lathe.
An object of the present invention is to provide an automatically operated lathe which makes it possible to effectively reduce a time required for one machining cycle in comparison with a conventional NC lathe, and which includes multi-functional properties capable of performing a secondary process during a period when a spindle does not rotate, as well as to provide a method for controlling such an automatically operated lathe.
Another object of the present invention is to provide an automatically operated lathe which makes it possible to easily program a synchronization command between plural control axes and to command a tool offset without varying the cutting feed speed of the tool, as well as to provide a method for controlling such an automatically operated lathe.
To achieve the above object, the present invention provides in one aspect thereof a method for controlling an automatically operated lathe provided with at least one spindle and at least one tool rest, comprising providing each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of either one of two types of transfer position data, one of which is a cam-reference data directing a transfer position as a function of a cam rotation quantity and the other of which is a time-reference data directing a transfer position as a function of an elapsed time; and processing each of the plural transfer position data provided in the form of either one of the cam-reference data and the time-reference data, to control a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, the method for controlling is provided, wherein the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes, and wherein the step of providing the transfer position data includes providing each of the plural transfer position data in the form of either one of the cam-reference data and the time-reference data in relation to each of the plural control axes.
Also, in the preferred embodiment, the method for controlling is provided, further comprising a step of designating a time-series allocation of the plural transfer position data in the sequence of machining programs, wherein the step of processing the transfer position data includes processing, in accordance with the time-series allocation as designated, each of the plural transfer position data provided in the form of either one of the cam-reference data and the time-reference data.
Also, in the preferred embodiment, the method for controlling is provided, further comprising a step of showing, in a form of a displacement diagram, each of the plural transfer position data provided in the form of either one of the cam-reference data and the time-reference data.
In this arrangement, it is advantageous that the method further comprises a step of designating a time-series allocation of the plural transfer position data in the sequence of machining programs on the displacement diagram, and that the step of processing the transfer position data includes processing, in accordance with the time-series allocation as designated on the displacement diagram, each of the plural transfer position data provided in the form of either one of the cam-reference data and the time-reference data.
The step of processing the transfer position data may include processing, as a function of a pulse number corresponding to the cam rotation quantity, the transfer position directed by the cam-reference data.
In this arrangement, it is advantageous that the method further comprises a step of providing a pulse-train generating source for generating any pulse train, and that the step of processing the transfer position data includes processing the cam-reference data by using a pulse train generated through the pulse-train generating source.
In this case, the pulse-train generating source may generate a pulse train corresponding to a rotation of the at least one spindle.
The present invention provides in another aspect thereof an automatically operated lathe, comprising a lathe bed; at least one spindle mounted on the lathe bed; at least one tool rest mounted on the lathe bed; a control device for controlling an operation of the at least one spindle and the at least one tool rest on the lathe bed; the control device including an input section permitting an entering of each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of either one of two types of transfer position data, one of which is cam-reference data directing a transfer position as a function of a cam rotation quantity and the other of which is time-reference data directing a transfer position as a function of an elapsed time; and a processing section processing each of the plurality of transfer position data entered through the input section in the form of either one of the cam-reference data and the time-reference data, to thereby generate a control signal for controlling a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, the automatically operated lathe is provided, wherein the at least one spindle and the at least one tool rest are capable of performing a relative feed motion along a plurality of control axes on the lathe bed, and wherein the input section of the control device permits an entering of each of the plurality of transfer position data in the form of either one of the cam-reference data and the time-reference data in relation to each of the plurality of control axes.
Also, in the preferred embodiment, the automatically operated lathe is provided, wherein the input section of the control device permits a designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs, and wherein the processing section of the control device processes, in accordance with the time-series allocation designated through the input section, each of the plurality of transfer position data entered in the form of either one of the cam-reference data and the time-reference data through the input section.
Also, in the preferred embodiment, the automatically operated lathe is provided, wherein the control device further includes a display section displaying, in a form of a displacement diagram, each of the plurality of transfer position data entered through the input section in the form of either one of the cam-reference data and the time-reference data.
In this arrangement, it is advantageous that the input section of the control device permits a designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs on the displacement diagram displayed in the display section, and that the processing section of the control device processes, in accordance with the time-series allocation as designated on the displacement diagram, each of the plurality of transfer position data entered in the form of either one of the cam-reference data and the time-reference data through the input section.
The processing section of the control device may process, as a function of a pulse number corresponding to the cam rotation quantity, the transfer position directed by the cam-reference data entered through the input section.
In this arrangement, it is advantageous that the lathe further comprises a pulse-train generating source for generating any pulse train, and that the processing section of the control device processes the cam-reference data by using a pulse train generated through the pulse-train generating source.
In this case, the pulse-train generating source may generate a pulse train corresponding to a rotation of the at least one spindle.
The present invention provides, in a further aspect thereof, a control device for use in an automatically operated lathe provided with at least one spindle and at least one tool rest, comprising an input section permitting an entering of each of a plurality of transfer position data required in a sequence of machining programs in connection with the at least one spindle and the at least one tool rest in a form of either one of two types of transfer position data, one of which is a cam-reference data directing a transfer position as a function of a cam rotation quantity and the other is a time-reference data directing a transfer position as a function of an elapsed time; and a processing section processing each of the plurality of transfer position data entered through the input section in the form of either one of the cam-reference data and the time-reference data, to thereby generate a control signal for controlling a relative feed motion between the at least one spindle and the at least one tool rest in the sequence of machining programs.
In the preferred embodiment, the control device is provided, wherein the input section permits designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs, and wherein the processing section processes, in accordance with the time-series allocation designated through the input section, each of the plurality of transfer position data entered in the form of either one of the cam-reference data and the time-reference data through the input section.
Also, in the preferred embodiment, the control device further comprises a display section displaying, in a form of a displacement diagram, each of the plurality of transfer position data entered through the input section in the form of either one of the cam-reference data and the time-reference data.
In this arrangement, it is advantageous that the input section permits a designation of a time-series allocation of the plurality of transfer position data in the sequence of machining programs on the displacement diagram displayed in the display section, and that the processing section processes, in accordance with the time-series allocation as designated on the displacement diagram, each of the plurality of transfer position data entered in the form of either one of the cam-reference data and the time-reference data through the input section.
The processing section may process, as a function of a pulse number corresponding to the cam rotation quantity, the transfer position directed by the cam-reference data entered through the input section.